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چكيده انگليسي :

D MIMO Spectral Efficiency Enhancement Using Precoding and Beamforming Techniques Samira Malekpour s malekpour@ec iut ac ir May 20 2016 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors Dr Mohammad Sadegh Fazel Dr Abolghasem ZeidabadinezhadAbstract MIMO systems with its reliability and high growth in sum rate without increasing the transmission power or bandwidth have been used in several recent wireless communication standards Meanwhile microcell and distributed antenna systemshave received the most attention due to the reduction of distance between the transmitter and the receiver and the resultingincrease in data rates When the antenna elements of a central antenna unit in a big cellular area are divided into severalseparate antenna units and distributed around the area so that every element is connected to a central processing unit placedin the center of the area a distributed antenna system is created In addition to spatial diversity this kind of system allowsfor large scale and small scale performance improvements such as reducing radiation power which in turn reduces inter cellinterference as well as increasing coverage and spectral efficiency Nevertheless the different degrees of path loss due todifferent distances between users and the distributed units create noticeable challenges in analyzing the efficiency of thesesystems Using MIMO capability in each smaller antenna unit in order to increase spectral efficiency and also concentratingradio signals in a particular direction can improve reliability of the communication link as well However according to thepropagation loss in high frequencies millimeter wave frequencies in order to have a better coverage in every macrocell thedirection of transmission should be changed towards the desired receiver and vice versa Moreover it is necessary to ensurea long range reception by compensating for the path loss in an optimal fashion The objective of an antenna array in form ofa spatial angular filter is to successfully send or receive a beam to from a desired direction and to create an effectivenull both in reception and transmission in order to eliminate transmission or reception of signals to from undesirabledirections This process is as effective in reducing interference as using a large directional antenna The formation of thisspatial filter in high frequencies millimeter wave frequencies in the presence of uniform random line of sight UR LoS stochastic channel provides a desired propagation phenomenon In this thesis in order to improve the performance of thecommunication network in millimeter wave frequencies we propose a method for beam forming based on the main beamforming and effective null forming Accordingly three communication scenarios have been analyzed In the first scenario the centralized scenario we consider a point to point communication between a multi antenna unit and a single multi antenna user In the second scenario cooperative scenario several multi antenna units send same information to a singlemulti antenna user In the third scenario multi user scenario each multi antenna unit is connected to the nearest multi antenna user independently According to the fact that each multi antenna unit has an antenna array spatial multiplexingcan also be provided in addition to the frequency time multiplexing of the beams It is noteworthy that the proposed beamforming scheme used at the transmitter and receiver is based on the SIR maximization approach Considering the designcriteria simulation results confirm the efficiency of the proposed technique in terms of the sum throughput of the network Key Words MIMO Distributed MIMO D MIMO Smart antenna array Beamforming and Pre coding Nullforming

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بهبود كارآيي طيفي سيستم هاي چند ورودي - چند خروجي توزيع شده با استفاده از تكنيك هاي شكل دهي باريكه و پيش كد گذاري

چند آنتني , آرايه آنتن هوشمند , شكل دهي صفر